Rock Me on the Water

July 1, 1989

Seth B. Golbey

Most pilots have never considered adding a seaplane rating to their certificates, and at first glance, it's not hard to understand why. Seaplanes have an exotic ambiance about them; the mental images they conjure are of bushplanes in the northern wilds, flying boats in the Caribbean, or even big amphibs providing support services in the oil patch. If your airport is like most, the sight of a Maule or Cessna on amphibious floats on your ramp is a noteworthy one. They have the aura of working machines — and so they are — but they also offer recreational opportunities that landplanes cannot. With a seaplane, a visit to your favorite fishing (or swimming) hole becomes a pleasant weekend diversion rather than a trying, often frustrating, exercise in leisure-time logistics. And even if you never plan to fly a seaplane on a regular basis, earning the rating can be one of the most pleasant and rewarding experiences of your aviation career.

Pilots love a challenge, and flying floats is one of the best. It is a much less expensive rating to earn than most — often for less than $500 — and it can be accomplished in much less time — two or three days will usually suffice. It is also a rating that you don't need lots of experience to pursue; it's a great first add-on for the low-time pilot. And, of course, earning the rating also counts as a biennial flight review. So leave your jacket and tie in the Bonanza, slip into shorts, T-shirt, and sneakers (the haute couture of the seaplane world), and read on as we explore the challenges of learning to fly floats.

When we say "seaplane," we might mean a flying boat (like a Lake or Republic Seabee amphibian), a floatplane (which uses pontoons to support the airplane), or an amphibious floatplane (equipped with pontoons that contain wheels that can be extended for operations at airports or for taxiing into and out of the water). You'll learn these distinctions in ground school. Because most primary training is accomplished in airplanes on "straight" floats, most of your preflight training will concern basic floatplanes.

Ground school, which usually takes an hour or two, introduces you to a new language, beginning with the structure of the floats. Every float is rated according to the weight of fresh water that it can displace, and each float most be able to support 90 percent of the allowable gross weight of the airplane. A float rated 1500, for example can displace 1,500 pounds of fresh water. A pair of 1500s can support an air plane of 1,666 pounds gross weight and still retain the 80-percent "minimum re serve buoyancy" mandated by Federal Aviation Administration regulations Attached to an airplane like a Piper J-3 which has a gross takeoff weight of about 1,350 pounds, these floats provide plenty of "excess reserve buoyancy.' This would be referred to as an "overfloated" airplane. Overfloating within certain limits, enhances water handling.

Each float is divided into compartments separated by bulkheads, which keep any water in the floats from sloshing about and changing the airplane's center of gravity during maneuvers such as the takeoff run; they also provide structural integrity to the float itself. Floats must have at least four compartments (most have more) and must be able to remain afloat with any two compartments filled with water. These compartments are pumped out before each flight to remove any condensation or leakage that could provide weight and balance problems on takeoff.

Other parts of the float include a rubber bumper at the bow (better get used to bow and stem, windward and leeward, port and starboard; marine terminology holds sway in water flying); a keel that strengthens the bottom of the float and supports the airplane when on dry land (the keel is strong enough to allow a floatplane to land on a solid surface if necessary); the sister keelson, which helps strengthen the float; the chine, which, along with the spray rail, helps deflect water to the sides during takeoff and landing and also serves to attach the sides of the float to the bottom; the step, which, like the step of a boat hull, allows the airplane to plane along the surface of the water; the skeg, which forms the afterbody of the keel; the retractable water rudder, which aids in directional control during certain maneuvers on the water; the deck, which you walk on; and the cleats, which are used in securing the airplane. Then there are the struts, spreader bars, and bracing wires that attach the float to the airplane and the cables used to operate the water rudders.

Floats are aerodynamic as well as hydrodynamic structures, so a properly equipped floatplane will handle as well in the air as its wheeled cousins. You'll generally notice some diminution in climb and cruise performance, however, because of the added drag (one exception is the J-3, which actually flies slightly faster with floats), as well as a penalty in terms of useful load. Most airplanes, though, have a lower stall speed when on floats. But the challenge here is not in the flying, it's in getting from wherever the floatplane is "parked" (or, more properly, moored, docked, beached, or ramped) to the air, and vice versa.

Floatplanes have no brakes; even with the engine at idle thrust, the airplane will make way through the water, Taxiing therefore takes on an added dimension. The standard taxiing technique is idle, or displacement, taxiing. Here, the floatplane is supported by the displacement of the floats and guided by means of a combination of the minimum necessary power (depending on wind conditions) and use of the water rudders, which you extend by means of a handle in the cockpit. The most common mistake is to use too much power. Idle taxiing is the preferred taxi technique because adequate airflow is available for engine cooling, visibility over the nose is relatively good, and there is a lessened chance of spray damage to the propeller. (Spray can "shot-peen" a propeller to total destruction in a very short time; maneuvers that throw spray toward the prop are to be avoided at all cost.) Idle taxiing is performed with full aft stick (unless taxiing with a strong tailwind). This helps keep the bows of the floats out of the waves and improves directional control. Control displacements are used just like when taxiing an airplane on land; i.e., keep the upwind wing down.

If the distance needed to be covered during the taxi is long and the water is not too choppy, you can taxi "on the step." This involves speeding the airplane up with power until hydrodynamic forces increase on the bottom of the float to the point that it is forced up onto its step. Back pressure on the stick is released to the point necessary to remain on the step (if the nose comes down too far, or is held up too high, porpoising will result). Water rudders are retracted for this maneuver, as the air rudder will be quite effective. Turns while step taxiing are more safely made when turning from upwind to downwind because the centrifugal force of the turn and the force of the wind tend to counteract one another. High-speed turns from downwind to upwind should be avoided because the two forces reinforce one another in tending to tip the airplane over.

On the water, the airplane's weathervaning tendency is much more pronounced than on land. The floatplane pivots around its center of buoyancy, which is a point about midway along the wetted area of the float. Sometimes the wind is too strong to allow you to turn the airplane from upwind to downwind using idle taxi techniques. On airplanes like the J-3, what is needed is to move the center of buoyancy aft, which exposes more of the fuselage forward of the CB to the wind and allows the wind to help swing the nose downwind. This can be done using a plow taxi turn in which power is added but nose-up elevator is maintained to keep the nose high. Water rudders are extended. As the floats start to rise out of the water, the center of buoyancy moves aft, allowing the downwind turn. Plow turns can also be used when you need good control in confined maneuvering spaces. Plow turns should be avoided whenever possible because (a) the engine is developing a lot of power but forward speed is low, so engine cooling is poor, (b) the nose-high attitude severely limits forward visibility, and (c) the spray problem is accentuated, especially in rough water. Some schools do not even teach the plow taxi for these reasons.

If the wind is too strong, or the water too rough, to allow a plow turn or a downwind taxi, the floatplane may be "sailed." With the nose into the wind, water rudders retracted, and the engine off, use full up aileron in the direction you want to sail (full right stick to sail to the right, for example) and full opposite rudder. You'll be moving backward, but you'll be headed in the right direction. If the wind is sufficiently strong, a little power can add to your control while sailing, but in this case, the control displacements are opposite those for power-off sailing, and you end up moving sideways instead of diagonally backward. With a little practice, a surprising amount of precision can be attained.

Anytime you are in doubt about controlling a floatplane on the water, the rule is: Cut the power and come full aft on the elevator control.

A normal takeoff is a straightforward affair. Make sure the carburetor heat is off, the takeoff area dear, the water rudder retracted, and the stick full back. (The CARS check fist — carb heat, area, rudder, stick — should be used before any maneuvering in a seaplane, whether in the water or in the air.) Apply full power. The bows of the floats rise. After a moment, they will rise a bit further; this is the signal that you are climbing onto the step. Release back pressure on the stick until the floats are planing along the surface. As the floatplane establishes itself on the step, you will be able to feel an acceleration as the drag on the floats diminishes. When you reach flying speed, a very small back pressure will lift you off, and you'll feel another acceleration as the floats come free of the water.

Before landing on an unfamiliar piece of water, you'll want to make a few circuits of the landing area at relatively low altitude (patterns are typically flown at about 500 feet agl) to assure that it is deep enough and free of obstructions (including boats that could, at the worst possible moment, cut across your landing path) both in the water and along the shorelines. You'll also want to ascertain the wind direction. In floatplane flying, you'll become much more sensitive to wind than you were before. Wind direction can be determined in any number of ways, including slick water at the upwind edge of the body of water, wave patterns, foam streaks, and so on. On a body of water of any size, you'll almost always be able to land and takeoff directly into the wind.

A power-off or power-on approach may be made, the important point being to touch down at the lowest possible speed. Roundout should be initiated when the bottoms of the floats are about 10 to 12 feet off the water. The one thing you do not want to do is get near the surface of the water in a nose-low attitude. A power-off approach and fullstall landing can be made, but height above the surface is hard to judge over water, so the safest technique is to flare to approximately the step-taxi attitude and touch down in a slightly nose-high attitude. Then power (if any) off, bring the stick full back as the airplane slows, and you will settle and stop in a remarkably short distance. A rough-water takeoff is the seaplane equivalent of a soft-field takeoff. A slightly nose-high attitude is maintained so that the airplane lifts off as soon as possible and at minimum airspeed. Then lower the nose and accelerate in ground effect or in a very slight climb. When climb speed is attained, proceed as you would normally.

A rough-water landing is similar to a soft-field landing. The point here is to touch down as gently as possible, so a little power is added after the nose is raised during the flare. The airplane is landed at minimum airspeed in a nose-high attitude.

Crosswind takeoffs and landings are much like they are in landplanes; use the appropriate normal or rough-water technique but take off or land with the upwind wing low while keeping the airplane tracking straight with rudder.

The most demanding situation a floatplane pilot faces is glassy-water operations, for which no analogue exists in landplane flying. When the surface of a body of water is absolutely smooth, depth perception evaporates. This is not so much the problem on takeoff that it is on landing, but takeoff has its own challenges. Glassy water makes it difficult for a float to break free of the surface tension that holds it to the water. Therefore, when the airplane is accelerating on the step, the right float should be lifted out of the water just before flying speed is attained. (You could lift the left float, but torque makes the right one easier to lift.) The airplane then accelerates on the left float, and the rotation is performed otherwise normally.

For landing, it is important to pick out a landmark at the approach end of the body of water. This landmark is known as the last visual reference (LVR). Approach the LVR with power off; the trick is to come as low over the LVR as it is possible to do safely. Over or just before reaching the LVR (never past it), the nose is raised to slightly higher than the normal landing attitude and power is increased to a level that will provide a rate of descent of no more than 100 to 150 feet per minute. Then do nothing except maintain the nose-up pitch and a wingslevel attitude. The airplane may seem to float on forever above the surface of the water, but it is critical not to try to flare visually; it just can't be done safely. If the attitude is properly maintained, the floatplane will slide onto the water in a breathtakingly gentle landing. Then power and stick back, as before.

There is obviously much, much more involved in being a knowledgeable and proficient seaplane pilot than we can touch on here. We haven't discussed, for example, the rules of the road when operating on water, or how to determine whether a body of water is open to seaplane operations, or how to do a proper preflight inspection. We also haven't talked about emergency procedures, or the special techniques involved in anchoring, mooring, docking, and beaching. We haven't gone into the unique attributes of flying boats or amphibians, either. Fortunately, there are plenty of sources of information that can fill in these gaps (see "For Further Reading," p. 48). .

Sure, there's a lot to learn. But there are few aeronautical challenges that provide as much fun for the time spent in their mastery as does floatplane flying. Once you've tried it, you may find yourself considering trading your wheels for floats, at least for those long summer days when a look out the window not only makes you think about flying, but about that old fishing hole as well.

For Further Reading

Plenty of good resources are available to the aspiring seaplane pilot. Here's a highly subjective list of some of the best and a couple of places where you can get them.

Start out with Chapter 15 of the FAA's Flight Training Handbook (AC 61-21A). Basic terminology and procedures are outlined here. If you don't already own a copy, which you should, the book is available at many fixed-base operations, from the Government Printing Office, or from the AOPA Air Safety Foundation.

Bar none, the best primer is How to Fly Floats by J. J. Frey, vice president of float manufacturer EDO Corporation. Frey goes into greater depth than the Flight Training Handbook and is particularly strong on technique; this is the standard text for most seaplane ground school courses. Available for $5 from Sporty's Pilot Shop, the Seaplane Pilots Association (SPA, 421 Aviation Way, Frederick, Maryland 21701), or EDO (Float Operation, 14-04 111th Street, College Point, New York 11356).

For a more detailed study, read Flying a Floatplane by Marin Faure. This copiously illustrated handbook takes you through the basics and on to advanced maneuvers; it also discusses the history of seaplanes and contains a useful section on U.S. and Canadian regulations. An appendix contains float manufacturers' names and addresses; an excellent bibliography is provided. This very comprehensive work is available for $17.95 from Sporty's or SPA.

A new book, Water Flying Concepts, by Dale De Remer, is the sine qua non for advanced wilderness seaplane flying. A technical yet eminently readable discussion of advanced techniques, plus sections on topics such as external loads, wilderness operations and survival, and seaplane camping make this an important work for the student and old pro alike. Available for $14.95 from Dr. De Remer, 1323 Noble Cove, Grand Forks, North Dakota 58201; from SPA; or from Like & Air, Incorporated, Post Office Box 442244, Eden Prairie, Minnesota 55347. — SBG

Seaplane Pilots Association

The Seaplane Pilots Association, or SPA, was formed in 1972 as a nonprofit organization whose main purpose was, and remains, to protect the water-flying rights of all seaplane enthusiasts worldwide. SPA works hard for its more than 4,200 members to eliminate seaplane restrictions and to open new waters for the enjoyment of its members.

Interest in water flying has never been more pronounced. More and more pilots afflicted by air traffic restrictions and airport access problems are perceiving water flying as a welcome opportunity to enjoy aviation without all the hassle. Seaplane and float manufacturers, along with many suppliers to the industry, report busy telephones. Interest in water-borne ultralight and kitplane assembly projects, as an entry-level approach to aviation, is booming.

On May 1, a master aviation hull and liability insurance policy was issued for SPA — the culmination of a long awaited realization of a less expensive alternative to market rates for hull and liability protection for SPA members. This is expected to be the single most important event in the history of the organization in terms of potential savings to members and as an incentive to join SPA.

In addition, membership brings the Water Flying Quarterly and Water Flying Annual publications. The association also publishes the SPA Water Landing Directory, which contains diagrams of seaplane bases and water landing sites, as well as much other useful information.

There are sound financial reasons for aircraft ownership. Beyond the money saved on overnight trips, delays caused by airlines, and other miscellaneous expenses, owning an airplane has definite tax advantages.